Global Water Footprint of Key Crops

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Global Water Footprint of Key Crops

In order to better understand water use and availability trends, scientists divide the Earth’s surface into river basins. This feature examines some of the river basins that are the most important from an agricultural perspective. In each basin, the primary source of water is precipitation. Rain and snow feeds the river and its tributaries, as well as groundwater, ponds, and lakes. Precipitation also adds moisture to the soil, and crops take up the moisture through their roots.

Most crops around the world are grown using only the soil moisture provided by rainfall. When this moisture is insufficient, farmers apply more water through irrigation. Some rain or irrigation water evaporates without benefiting the plant, while some transpires through the plant's tissues during photosynthesis and returns to the atmosphere. Water transformed into vapor in either of these ways is not available for use again in that local area, so in practical terms, it is lost or "consumed."

Different crops have different water needs, which vary with the climate in which they’re grown. Scientists at the University of Twente in the Netherlands have used modeling techniques to estimate the amount of water consumed by the various crops grown in river basins around the world.

Click here to see for an interactive look at the impact of some of the most important crops produced for U.S. consumption:
http://j.mp/GTn6Ok

Source: National Geographic

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